This invention is an improvement on my previously issued U.S. Pat. No. 3,737,061.
It has been proposed heretofore to provide tractor bodies with liftable bed features in combination with removable storage units to be carried thereon. The truck trailer is maneuvered into position beneath the storage unit, the bed is raised for transport of the unit and the unit is removed by lowering the bed at the delivery destination. Examples of such arrangements may be seen in U.S. Pat. No. 2,596,838; 2,670,866; 2,676,783; 3,362,552 and the above-mentioned U.S. Pat. No. 3,737,061.
In each of the several liftable truck bed systems described in these listed patents, the liftable bed is raised vertically by an independent actuator system comprising one or more actuators which operate directly upon the liftable bed, or through linkages to raise the entire bed the requisite height for travel above the fixed bed. As stated in U.S. Pat. No. 2,676,783, such actuation must be critically designed in order to prevent jamming and the severe stresses of over balance, over hanging and deflection of the supplemental (liftable) bed.
It is the objective of the present invention to disclose an improved, simplified technique and apparatus for a liftable truck trailer which will accommodate light to extremely heavy loads with great reliability.